# .NET auto-instrumentation not working **URL:** \ **Category:** APM\ **Tags:** dotnet\ **Created:** [August 4, 2026, 12:34pm UTC](https://discuss.elastic.co/t/net-auto-instrumentation-not-working/388966 "2026-08-04T12:34:11Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Umut](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/umut/32/147682_2.png) [@Umut](https://discuss.elastic.co/u/Umut)\ **Post date:** [August 4, 2026, 12:34pm UTC](https://discuss.elastic.co/t/net-auto-instrumentation-not-working/388966/1 "2026-08-04T12:34:12Z")
**Kibana version** : v 7.16.3 **Elasticsearch version** : v 7.16.3 **APM Server version** : v 7.16.3 **Original install method (e.g. download page, yum, deb, from source, etc.) and version**: [GitHub - elastic/apm-agent-dotnet · GitHub](https://github.com/elastic/apm-agent-dotnet) **Is there anything special in your setup?** Load balancer in front of the APM servers **"** [2026-08-03T18:19:42.2740259+03:00] [WARN] Assembly.Load failed for Elastic.Apm.Profiler.Managed, Version=1.34.0.0, Culture=neutral, PublicKeyToken=ae7400d2c189cf22, falling back to Assembly.LoadFrom from D:\ElasticApm\net462 System.IO.FileNotFoundException: Could not load file or assembly 'Elastic.Apm.Profiler.Managed, Version=1.34.0.0, Culture=neutral, PublicKeyToken=ae7400d2c189cf22' or one of its dependencies. The system cannot find the file specified. File name: 'Elastic.Apm.Profiler.Managed, Version=1.34.0.0, Culture=neutral, PublicKeyToken=ae7400d2c189cf22' at System.Reflection.RuntimeAssembly.\_nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) at System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, RuntimeAssembly reqAssembly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean forIntrospection) at System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) at System.Reflection.Assembly.Load(String assemblyString) at Elastic.Apm.Profiler.Managed.Loader.Startup.TryLoadManagedAssembly()" "Line 122: [2026-08-04 11:28:07.244 +03:00][7][Error] - {ElasticApmModule.#2} Processing EndRequest event failed +-\> Exception: System.NullReferenceException: Object reference not set to an instance of an object. Line 108: [2026-08-04 11:28:07.239 +03:00][9][Error] - {ElasticApmModule.#2} Processing BeginRequest event failed +-\> Exception: System.NullReferenceException: Object reference not set to an instance of an object. at Elastic.Apm.AspNetFullFramework.ElasticApmModule.ProcessEndRequest(Object sender) at Elastic.Apm.AspNetFullFramework.ElasticApmModule.OnEndRequest(Object sender, EventArgs e) at Elastic.Apm.AspNetFullFramework.ElasticApmModule.ProcessBeginRequest(Object sender) at Elastic.Apm.AspNetFullFramework.ElasticApmModule.OnBeginRequest(Object sender, EventArgs e)" ---
**Author:** ![stevejgordon](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/stevejgordon/32/80912_2.png) [@stevejgordon](https://discuss.elastic.co/u/stevejgordon)\ **Post date:** [August 4, 2026, 2:42pm UTC](https://discuss.elastic.co/t/net-auto-instrumentation-not-working/388966/2 "2026-08-04T14:42:42Z")
Hi, @Umut. We'll likely need some more context to help further, such as the exact steps you used to install and configure the profiler. A few initial things to check/try. 1. Verify the net462 folder contents - check that D:\ElasticApm\net462\Elastic.Apm.Profiler.Managed.dll exists and its file version matches 1.34.0. 2. Re-run the install script/re-extract the zip - the profiler zip ships with both net462/ and net472/ subdirectories; both must be present. 3. If still failing after that, add COMPlus\_LoaderOptimization=1 to the IIS app pool environment variables. 4. For the ElasticApmModule NRE - if you've added the module to `web.config` manually, you also need to call Agent.Setup() in their startup code, or remove the manual `web.config` entry and let the profiler register it automatically (once step 1 is fixed). 5. If this still fails, [enable global file logging](https://www.elastic.co/docs/troubleshoot/observability/apm-agent-dotnet/apm-net-agent#collect-logs-globally) at trace level and review the logs for further information which may help pinpoint the issue. 6. Strongly consider upgrading the APM Server — 7.16.x is end-of-life and may not correctly process intake from a 1.34.0 agent. Can you also let us know: - The Windows Server version and edition (e.g. Windows Server 2019 Standard) - The .NET Framework version installed on the server - you can check this by running the following in PowerShell: `Get-ChildItem 'HKLM:\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full' | Get-ItemPropertyValue -Name Release` - The IIS application pool pipeline mode - in IIS Manager, check the app pool's Managed Pipeline Mode setting (Integrated vs Classic)